def __init__(self):
        """
        We do nothing more than calling the base constructor and setting the _calculation_process_type
        afterwards to the correct type (our own one).
        """
        Calculation.__init__(self)

        self._calculation_process_type = BasicCalculationProcess
 def __init__(self):
     Calculation.__init__(self)
     self._calculation_process_type = DeriviedCalculationProcess
    def __init__(self):
        Calculation.__init__(self)

        self._calculation_process_type = SimpleCalculationProcess
 def __init__(self):
     Calculation.__init__(self)
     self._calculation_process_type = DeriviedCalculationProcess